feat(MR): [MR-638] Include best-effort calls in xnet_compatibility …

…test

Make both guaranteed response and best-effort calls in the subnet upgrade-downgrade `xnet_compatibility` test.

rs/tests/message_routing/xnet/xnet_compatibility.rs

@@ -146,11 +146,7 @@ pub async fn test_async(env: TestEnv) {
         .map(|(_, _, node)| node)
         .map(|node| runtime_from_url(node.get_public_url(), node.effective_canister_id()));
 
-    // Only guaranteed response calls, for now.
-    // TODO(MR-638): Also enable best-effort calls, when supported on mainnet.
-    let call_timeouts = [None];
-    let xnet_config = xnet_slo_test_lib::Config::new(2, 1, Duration::from_secs(30), 10)
-        .with_call_timeouts(&call_timeouts);
+    let xnet_config = xnet_slo_test_lib::Config::new(2, 1, Duration::from_secs(30), 10);
     let long_xnet_config = xnet_slo_test_lib::Config::new_with_custom_thresholds(
         2,
         1,